Fat-liquoring of tanned hides and skins



w Sept. 2, 1941 FAT-LIQUORING OF TANN ED HIDES AND SKINS William W. Stapler, River-dale, N. J., assignor to Hercules Powder Company, Wilmington, Del., a

corporation of Delaware Application September 13, 1940, Serial No. 356,647

No Drawing.

8 Claims.

This invention relates to the treatment of hides and skins, and in particular concerns an improved method and composition for the fatliquoring of tanned hides and skins..

The manufacture of leather from the hides and skins of various animals essentially comprises a cleaning treatment to remove flesh, hair, dried blood, insoluble protein matter, etc. from the crude hides; a degreasing treatment whereby at least a portion of the fatty substances are removed from the hide tissues in order to permit better penetration of the tanning liquor; and

'thereafter subjecting the cleaned and degreased hides to the actual tanning operation. After tanning, the hides must be ,treated to replace the natural oils and fatty substances which were removed during the degreasing and tanning operations in order to lubricate the hides and render the finished leather soft and pliable and more resistant to tearing, Such treatment, known in the artsas fatliquoring, usually consists in agitating the tanned hides in a rotary drum or similar device with aqueous emulsions of fatty or oily materials which will penetrate into the pores of the hides, thereby securing the desired lubricating and softening effect. ,Typical fatliquoring compositions usually consist of an oil, -such as cod-liver oil, neatsJoot oil, oxidized codliver oil, and the like; an emulsifying agent, such as sulfonated castor oil, soap, egg yolk, etc.; and in some instances a buffer, such as borax or sodium carbonate, to adjust the acidity.

The fatliquoring compositions heretofore em- V ployed, however, have not been entirely satisfactained in the outer layers of the skin and relatively little in the inner layers. This results in I uneven shrinkage of the skins upon drying and a roughened grain surface, and renders subsequent operations, such as bufiing, glazing, etc., very diflicult.

It is accordingly an object of the present invention to provide an improved method and composition for fatliquoring whereby tanned hides and skins are more uniformly fatliquored with respect to the different body portions thereof. A further object is to provide such a method and composition whereby tanned hides and skins are fatliquored more uniformly with respect to. their thickness. Other objects will be apparent from the following detailed description of the invention.

I have found that the above objects and attendant advantages may be secured by fatliquoring the tanned hides and skins, before or after dyeing, with a water emulsion of a fatliquoring composition to which has been added a small amount of an aliphatic polyhydric alcohol ether ployed in varying proportions, and a variety of' emulsifying agents may be used. Among the oils commonly used may be mentioned cod-liver oil, neats-foot oil, oxidized cod-liver oil, sulphonated neats-foot oil, etc. Suitable emulsifying agents are sulphonated cod-liver oil, Turkey red oil, soap, egg yolk, etc. In general, it is desirableto adjust the composition of the fatliquoring emulsion so that practically all of the oil is absorbed by the hides, thus allowing the spent liquor to be discarded with as little loss of oil as possible. Usually the amount of oils in the composition will vary from about 3 to about 10 per cent by weight of the dry hides.

The terpene ethers which are essential ingredients of the fatliquoring compositions of the invention are those formed by the addition of a lower aliphatic polyhydrlc alcohol, 1. e. an aliphatic polyhydric alcohol containing not more than six carbon atoms, such 'at ethylene glycol, propylene glycol, glycerol, sorbitol, trimethylene glycol, diethylene glycol, etc., to a double bond of an unsaturated terpene compound, e. g. terpinene, dipentene, alphapinene, terpineol, etc., or mixtures thereof, such as turpentine and turpentine cuts. The preparation of such additive terpene ethers is described in detail in U. S. Patent No. 2,136,011. While any additive lower aliphatic polyhydric alcohol ether of an unsaturated terpene compound may be employed in accordance with the invention, the ethylene glycol ethers of unsaturated terpenes, particularly turpentine, have been found to be particularly applicable because of their low cost and high efiiciency in promoting uniform fatliquoring. The proportion of. terpene ether employed in the fatliquoring composition varies widely, depending upon the particular composition used. Ordinarily, however, compositions containing the terpene ether in an amount representing from about 1 to about 20 per cent by weight of the oils present will be found most satisfactory.

In some instances, it may be advisable to include in the composition a small amount of a protective colloid to act as a stabilizing agent for the emulsion. A great variety of watersoluble colloidal substances may be used for this purpose, among which may be mentioned albumin, agar-agar, gum arabic, and methyl cellulose.

When employing the new compositions provided by the invention, the fatliquoring process is carried out in the same manner heretofore employed, 1. e., by agitating water-wet tanned hides, such as cow hides, calf skins, sheep skins, and the like, in a rotating drum or similar device with .an aqueous emulsion of the fatliquoring composition until the desired amount of oil, e. g. from about 0.5 to about 5 per cent by weight, based on the weight of the hides has been absorbed by the hides. Such treatment is usually carried out at a temperature of 100190 F. for from 80 minutes to 1 /2 hours, after which the hides may be removed from the drum and subjected to further steps in the process of leather manufacture, such as dyeing, glazing, etc.

The following examples illustrate several ways in which the principle of the invention has been applied, but are not to be construed as limiting the same.

Example I Seven hundred and fifty pounds of tanned cowhides were placed in a rotating drum and the following fatliquoring composition:

Ethylene glycol ether of turpentine emulsified in 85 gallons of warm water was added. The hides were tumbled in the emulsion for 40 minutes at a temperature of approximately 180 F., after which the liquor was drained from the drum and the hides were rinsed with water. The hides so treated were smooth and pliable and were relatively uniformly fatliquored throughout.

Example II In order to demonstrate the advantages of fatliquoring compositions containing terpene ethers, a tanned kid skin was split lengthwise and the halves designated as Sample A and "Sample B, respectively. Sample A was treated vith a typical commercial fatliquoring emulsion, whereas Sample B was treated with the same composition to which had been added 10- per cent of ethylene glycol ether of turpentine based on the weight of the oils present in the composition. Both treatments were carried out by tumbling the sample in the emulsion for 30 minutes at a temperature of about 150 F., after which the samples were removed from the liquor and rinsed with water. Rectangular specimens were then cut from different body portions of each sample and were analyzed for grease content by solvent extraction. The following data were obtained:

Percent grease Specimen No. Out from-- Sample A Sample B Rump 2. l5 0. 60 Back 1. 10 0. 50 Neck 0. 0. 44 Center 1.50 0. 54 Hindl l. 08 0. 76 Belly l. 67 0. 97 Fore leg 0. 99 0. 65

Mean percent grease 1. 33 0.64 High percent grease 2.15 0. 97 Lowpercent grease 0. 80 0. 44 Maximum percent deviation from mean.-. 62. 0 52. 0 Average percent deviation from mean. 29. 0 20. 0

It will be noted from the above data that although the sample fatliquored in the composition containing the terpene ether contained less total grease than the sample fatliquored in the usual manner, the former contained a much more even distribution of the grease. If desired, the total grease content could have been increased merely by continuing the treatment for a longer period of time or by the use of a more concentrated fatliquoring emulsion.

Other modes of applying the principle of my invention may be employed instead of those explained, change being made in either the process or ingredients disclosed, provided the process or the ingredients stated in the following claims, or the equivalent of such stated process or ingredients, be employed.

What I claim and desire to protect by Letters Patent is:

1. A composition for use in the fatliquoring of tanned hides and skins comprising an oil, an emulsifying agent therefor, and a minor amount of an additive lower aliphatic polyhydric alcohol ether of an unsaturated cyclic terpene compound.

2. A composition for use in the fatliquoring of tanned hides and skins comprising an oil, an emulsifying agent therefor, and an amount of an additive lower aliphatic polyhydric alcohol ether of an unsaturated cyclic terpene compound representing from about 1 to about 20 per cent by weight of the oil.

3. A composition for use in the fatliquoring of tanned hides and skins comprising an oil, an emulsifying agent therefor, and a minoramount of an additive ethylene glycol ether of an unsaturated cyclic terpene compound.

4. A composition for use in the fatliquoring of tanned hides and skins comprising an 011, an emulsifying agent therefor, and a minor amount of the additive ethylene glycol ether of turpentine.

5. A composition for use in the fatliquoring of tanned hides and skins comprising an oil, an emulsifying agent therefor, and an amount of the additive ethylene glycol ether of turpentine representing from about 1 to about 20 per cent by weight of the oil.

6. The process which comprises fatliquoring of tanned hides with a water emulsion of a fatliquoring composition containing a minor amount of an additive lower aliphatic polyhydric alcohol ether or an unsaturated cyclic terpene compound.

7. The process which comprises treating tanned hides with a. water emulsion of a fatliquoring composition containing an additive lower aliphatic polyhydric alcohol ether of an unsaturated cyclic terpene compound in an amount representing from about 1 to about 20 per cent by weight of the oils present in said composition.

8. The processwhich comprises treating tanned hides and skins with a, water emulsion of a fatliquoring composition containing the additive I ethylene glycol ether of turpentine in an amount representing from about 1 to about 20 per cent by weight of the oils present in said composition.

' W. STAPLER. 

